1.5 mm biomedical implants made of sugar polymers and other materials could be used to efficiently treat diseases such as diabetes(Credit: Andrew Bader, Omid Veiseh, Arturo Vegas, Anderson/Langer Laboratory, Koch Institute at MIT)

A team of researchers
from MIT has discovered that creating body implants at a certain
size maximizes the amount of time they can spend operational in the
body before being neutralized by the immune system. In the future,
the research could lead to longer term treatment avenues for diseases
that could do away with the need for painful and repeated injections.

Without doubt, the
human immune system is a wondrous thing. Over the course of our
species' short existence, it has protected us and evolved with us,
but it also has the capacity to interfere and stymie avenues of
treatment offered by advances in medical science. Such is the case
with body implants, which are increasingly used as a long-term drug
delivery method.

The study that led to
the discovery started seven years ago as an attempt to create an
artificial pancreas, in order to treat diabetes. The study aimed to
replace an individual's islet cells, which are responsible for
detecting high concentrations of blood sugar and trigger the release
of insulin from the pancreas. These cells cease to function in
individuals suffering from Type 1 diabetes, preventing the body from
coping with the sugar build-up.

During the
trial, the team implanted a series of
pancreatic islet cells encased in alginate implants directly into the
abdominal cavity of diabetic mice, which would mimic the functions of a healthy pancreas, making insulin
injections a thing of the past. However, the newly-implanted cells
would be incapable of performing their new function if they were
covered by scar tissue.

The
team discovered that larger implants measuring 1.5 mm in diameter
were better suited to avoiding scar tissue build-up when compared to
smaller 0.5-mm variants. The smaller implants were found to be
engulfed in scar tissue and ceased to function at around the four-week mark, however the 1.5-mm implant continued to function for an
impressive six months after insertion. Furthermore, the larger
implants were able to respond to changes in glucose levels while
attracting less attention from the rat's immune cells.

Over the course of the
study, the team trialled the two sizes of implants constructed out of
stainless steel, glass, polystyrene, and polycaprolactone. It was
discovered that the results invariably favored the larger analogue.
The research represents a promising step forward in implant
survivability, and could change the lives of millions suffering from
diseases such as Type 1 diabetes

A paper on the team's
research is available on the online journal Nature Materials.